Purification of naphthenic acids



Patented at. BL 1936 2,035,142 runmcsrron or mmrrnnmc ACIDS Frederick J. Ewing, Pena, Oaliiklassignor to Union Oil Company of California, Los Angeles, Caliih, a corporation of California No Drawing.

Application March 12, 1934, Serial No.-'I15,181

22 Claims. (or. 260-108) This invention relates to naphthenic acids and more particularly refers to a process for their deodorization and decoloration.

It is an object of my invention to present a simple, eiiicient and thoroughly satisfactory process for obtaining naphthenic acids of a light color and bland odor.

Naphthenic acids, such as may be obtained by acidifying various alkaline liquors arising during the refining of petroleum or shale oil fractions, constitute a complex mixture of acidic compounds containing principally carbon, hydrogen and oxygen. They range from comparatively low boiling liquids to materials which are solid or semi-solid at ordinary temperatures. Their viscosities as well as their boiling points are generally closely correlated to the viscosities and boiling points of the hydrocarbon fractions in which they are present.

The crude naphthenic acids which are obtained by acidifying the alkaline liquors referred to above, contain varying amounts of phenols and carbonaceous materials and they possess a very dark to black color and a disagreeable odor. When these crude acids are freed from phenolic materials by careful acidification, neutralization and distillation as hereinafter described to produce what will hereinafter be called semi-refined acids, vthe amount of carbonaceous materials appears to increase as a result of which 3 to 5% thereof and sometimes even greater amounts have been encountered in the dephenolized naphthenic acids. The major portion of this carbonaceous material is present in afinely suspended or colloidal stateand is in most instances not removable by settling or centrifuging. The presence of this material is partially responsible for the dark and turbid color of the 'naphthenic acids and renders their saleas a commercial product prac- 40 tically impossible. It is, therefore, desirable to obtain naphthenic acids which are substantially free from these undesirable materials.

It hasbeen customary to distill the naphthenic acids to remove this carbonaceous material. However, this distillation is not applicable in all in-.

stances in that itis usually accompanied by plugging of the still due. to the presence of the aforementioned carbonaceous material. Moreover, the equipment used for this distillation is'subject to a rapid deterioration due to the corrosive action of the naphthenic acids on iron or onother metals normally used in the construction of stills; The naphthenic acids which are recovered as an over- A head product of such a distillation are of a substantially improved color, but this color on standing rapidly darkens and in some instances becomes nearly as dark as before distillation.

A more'efilcient and satisfactory methodfor removing this carbonaceous material consists in treating the crude or semi-refined naphthenlc acidsv'vith any of the common oxygen-containing inorganic acids, such as sulphuricacid of suitable concentration, whereby a coagulation and separation of this carbonaceous material is brought about. The product obtained by this method of treatment which will be described in greater detail later on, is of a somewhat improved color but still is inapplicable without further treatment in any instances where a light colored product is desired.

I have discovered that naphthenic acids from which the carbonaceous materials have been removed by either of the two above identified processes or by any other physical or chemical means such. as those' hereinafter set forth, may be worked up into a product of excellent light color I which does not change or darken on exposure,

and bland odor, by treating them subsequently to the removal of the carbonaceous materials with an adsorbent material such as clay, fullers earth,

Filtrol or activated carbon. By so operating, a

for further purification by means of the adsorb.-

ent.

While it is customary to remove the residual inorganic acidity from the naphthenlc acids which have been treated with an oxygen-containing inorganic acid such as sulphuric acid for the removal of the admixed carbonaceous materials, experiments have indicated that the treatment with the adsorbent material may be substantially improved by eliminatingthe water wash for the removal of this inorganic acidity, and contacting the naphthenic acidswith the adsorbent-imaterial in the presence of small amounts-flit.- an

inorganic acid thus remaining in the naphthenic acids. As a slight modification of thet jabove method of treatment, I may activate or other adsorbent with small amounts of sulphuric acid or any of the other acids set forth herein by adding these acids to the adsorbent and treating thenaphthenic acids with the mixture of adsorbent and acid. Activation of the clay'with acid salts, i. e. a salt which on solution liberates hydrogen ion, produces substantially identical results as in the case where an inorganic acid is used for activating the adsorbent. If desired, I may also add my inorganic acid directly to the naphthenic acids before adding the adsorbent material, whereby the same effect of activation of the adsorbent is obtained.

Therefore, my invention broadly resides in a process for obtaining naphthenic acids of a stable light color and bland odor which comprises removing the carbonaceous material present in these acids and subsequently treating the product so obtained by means of an adsorbing agent.

My invention likewise extends to a process for purifying and decolorizing naphthenic acids wherein the adsorbing agent used has been activated or treated with an inorganic acid such as sulphuric acid or with an acid salt such as sodium acid sulphate or sodium acid phosphate or the like.

The term alkaline liquor referred to earlier in this specification relates not only to the alkaline solution containing naphthenic acids and other materials taken up by the alkali on treating a petroleum fraction but also relates to the alkaline solution obtained by treating the extract phase which is formed on treating a petroleum fraction with a selective solvent such as liquid sulphur dioxide, dichlorethyl ether, 'nitrobenzene, furfural, isopropyl alcohol, dimethyl sulphate, etc., with caustic soda, caustic potash or any other alkaline reagent.

When an alkaline liquor, arising on treatment of petroleum fractions such as any of those described above, is acidified with any of the well known inorganicacids a distinct phase separates out which phase is then adjusted by means of sodium carbonate or sodium hydroxide (or their equivalents) to apH of about 9. By so operating there is formed a mixture consisting of sodium naphthenates, phenols and admixed hydrocarbone which then subjected to distillation which removes the phenols and hydrocarbons overhead. The still bottoms then consist of sodium naphq thenates, which, when dissolved in water form a solutionfrom which the semi-refined acids are obtained by the addition of a mineral acid such as sulphuric acid.

These semi-refined naphthenic acids contain from 3 to of carbonaceous material, only a small fraction of which is removable by settling or centrifuging. Apparently this material 'is present in some kind of colloidal suspension which renders its separation extremely difficult. In addition, they are of a red to dark black color rendering their use as a commercial product practically impossible.

In a co-pending application, Serial No. 696,914, there is set forth a process for removing carbonaceous materials from, crude or semi-refined naphthenic acids which process, in its simplest aspect, relates to the treatment'of naphthenic acids with oxygen-containing inorganic acids of such concentration that the formation of emulsions is substantially prevented and a ready separation of the sludge formed upon acid treatment may be realized. For instance, sulphuric acid, having a concentration between approximately 50 and 83% has been found especially suitable.

'While any oxygen-containing inorganic acid such as iodic acid, chloric acid or bromic acid has been disclosed as suitable'for the-separation of the carbonaceous materials, we preferably use an oxygen-containing inorganic acid chosen from the class comprising sulphuric, phosphoric or nitric acid. The amounts of these acids to be used are relatively small and range from V to volume percent of the naphthenic acids.

\ If desired, the acid treatment referred to above, may-be carried out in the presence of a hydrocarbon diluent such as liquid propane, butane, cieaner's naphtha (a petroleum fraction boiling between 200-300 F.) benzol or the like. The addition of any of the above mentioned diluents greatly facilitates the separation of the sludge formed as a result of the acid treatment.

I have discovered in connection with the present invention that a similar facilitation of the sludge settling may be brought about by increasing the temperature of the acid treatment to temperatures ranging from approximatelfiy 100 to 200 F.

While in the above identified application it is 4 indicated that the strength of the acid used for the removel of the carbonaceous materials should preferably be between 50 and 83%, I have found that acids of greater concentration may be used as well and that such acids are especially effective when a naphthenic acid product of light color is desired. As such concentrated acids are more or less miscible with the naphthenic acids, steps must betaken to provide for the removal of these acids as well as for the acid sludge. Thus 95% sulphuric acid, fuming sulphuric acid (containing about dissolved S03) as well as sulphuric acid having a concentration of between 83 and 95%, tend to be substantially miscible with the naphthenic acids.

When the impure naphthenic acids containing carbonaceous materials are contacted with /2 to 10 volume percent of sulphuric acid having a concentration substantially that set out above, no separation into phases takes place, although in some cases the carbonaceous materials agglomerate. However, when portions of more dilute sulphuric acid (e. g. sulphuric acid of 60% concentration) are added to the mixture of impure naphthenic acids and the highly concentrated sulphuric acid, a separation into a naphthenic acid" phase and a phase consisting ofsludge, sulphuric acid and carbonaceous materials readily takes place as soon as the total acid concentration has been reduced to approximately 83%. The carbonaceous materials are found in the sludge and sulphuric acid layer.

Another method of obtaining phase separation when such concentrated acids are being used to obtain a higher degree of decolorization and deodorization consists in diluting the naphthenic acids either before or after treatment with the concentrated sulphuric acid, with a material capable of reducing the solvent power of the sulfuric acid for the naphthenic acids. Liquid propane, cleaners naphtha, petroleum ether or other light parafiinic solvents maybe used for this purpose. Aromatic hydrocarbons, such as benzol,

toluol or their homologues may be used for the purpose indicated above but are not as desirable as the paraflinic solvents on account of their solubility in the concentrated sulphuric acid. The

- above mentioned diluents may be removed from the naphthenic acids by distillation or by extracting the mixture of naphthenic acids and diluent with an alkaline material, such as caustic soda and liberating the naphthenic acids from their salts so produced by means of an inorganic acid such as H2804, HCl or the like.

The so treated acids are then treated'with the tioned acid treatment are contacted with an ad-,

, sorbent material while agitating the mixture of 300 F. After filtering off the adsorbent and,

either-by air or by mechanical means, no improvement in color or odor of the naphthenic acids is brought aboutafter filtering off the latter from the adsorbent. Even in the case where the naphthenic acids and adsorbent were heated to temperatures substantially in excess of atmospheric, no improvement in the color thereof could be noted.

When, however, the carbonaceous materials are removed from the naphthenic acids by means of any of the oxygen-containing inorganic acids set forth in the above identified co-pending application or by any other means and the so treated acids are subjected to a treatment with an adsorbent material a vast improvement in the color and odor-of the final product as compared with the crude or semi-refined acids is brought about.

For example, in a preliminary experiment, impure naphthenic acids which had been treated with 0.5% by volume of 80% sulphuric acid for purposes of -removing the carbonaceous materials admixed therewith, and which had a color in excess of 8 N. P. A., were contacted with 10% of fullers earth for 5 minutes at a temperature the materials taken up thereby, naphthenic acids having a color of from 4% to 5 N. P. A. was obtained. The same acids, without preliminary acid treatment, when contacted with the same adsorbent under identical conditions showed no improvement in color whatsoever.

Considering my process in greater detail, a charge of crude or semi-refined naphthenic acids contaminated with carbonaceous materials andhaving a dark red to black color, is treated with an oxygen-containing inorganic acid such as sulphuric acid. The amount of acid used may vary between V to 10 volume percent of the naphthenic acids. The concentration thereof is chosen preferably between 50 and 83%. The mixture of inorganic acid and naphthenic acids is agitated with air or by mechanical means preferably for a period of from 15 to 30 minutes. Just be- The naphthenic acids, treated as indicated above, have a much improved color but are still too dark for a commercial product. These acids are now mixed at ordinary temperatures or at least at temperatures below the boiling point of water, with the adsorbent, the amount of the latter being somewhere between approximately 8 and 20%, depending upon the particular charge of the naphthenic acids and the degree of decolorization desired. The mixture of naphthenic acids and adsorbentis heated while agitating with air or by other means, such as a mechanical stirrer up to a temperature ranging from approximately down and the. mixture is maintained at this temperature for a period of approximately 2 to 5 minutes. The agitation isthendiscontinued, and the purified and decolorized naphthenic acids are separated from the adsorbent by filtering them while still in a heated condition througha suitable filtering device such as a Sweetland filter.

It is not essential that the filtering process takes place at an elevated temperature. However, the

viscosity of the naphthenic acids at an elevated temperature is such to allow a more rapid filtration. The naphthenic acids so obtained have a color of from4 to 6 N. P. A. as compared with a color in-excess of 8 N. P. A.'before treatment with the adsorbent.

As a slight modification of the above operation, it may be desirable in connection with the purification of the naphthenic acids to eliminate the water wash of the naphthenic acids for re- I moval of the inorganic acidity and thus leave a color than one which had been water washed beiore treatment with the adsorbent. It is believed that the presence of the inorganic acid tends to activate the-adsorbent materiaL If for any reason a water wash of the naphthenic acids should be deemed desirable, the adsorbent may be activated by addition of small amounts of an inorganicacid such as that used for the removal of the carbonaceous materials or these acids may be directly added to the naphthenic acids before treatment with the adsorbent as pointed out above. acid sulphate, sodium acid phosphate or the like may be substituted for the inorganic acids and produce almost identical results. It has been found advantageous, especia ly in the case wher the residual inorganic acid is used for activating the adsorbent material, to introduce a small amount of water with the adsorbent, or adding the adsorbent in the form of ,a water containing slurry. The presence of the water app-ears to cause a better dispersion of the inorganic acid temperature.

limit is largely controlled by the boiling point and and hence a better-activation of the adsorbent material.

The amount of the adsorbent to be used will vary withthe naphthenic acid stock to be treated, the degree of decolorization and the particular 'Acid salts such as sodium f r adsorbent used. 'In general, amounts of. from" 8 to 20% of the adsorbent material as indicated above are sufllcient, although in certain instances where .a light colored product is desired, from 40 to 51% of the adsorbent material may be required.

, The treating temperature with the adsorbent have been made at temperatures of. 400. F. or

above. The above temperature range is merely my preferred operating temperature. Naphthenic acids, freed from carbonaceous materials by any of the processes set forth herein, show an improvement in color even when treated at room The upper treating temperature flash point of the naphthenic acids.

The time interval during whichthe naphthenic acids are contacted with the adsorbent material may vary over a wide'range. In general, 2 to 15 minutes are sufficient to bring bout the desired The following specific examples are illustrative of my invention:

Example 1 Fifteen hundred (1500) cubic centimeters of semi-refined naphthenic acids containing from 3 to 5% of carbonaceous materials were agitated with 75 cubic centimeters of 80% sulphuric acid for one-half hour. Immediately before the agl tation was stopped, 5 grams of diatomaceous earth were added to the mixture to facilitate .the settling of the sludge. The naphthenic acids, now substantially free from the above mentioned carbonaceous materials,=were washed with hot salt -The finished product in each instance had an acid number of from 289-290, as compared with an acid number of 284 before treatment.

The following example is illustrative of the improved decolorizing action of the adsorbent when small amounts of sulphuric acid are left in the naphthenic acids which in this caseis accomplished by eliminating the water wash. The stock. used consisted of semi-refined naphthenic acids which had been agitated with 5 volume percent of 80% H2SO4. (About 1% of clay was added to facilitate the settling of the sludge.) The re sults of the treatment of these acids with the adsorbent in comparison with naphtheuic acids water and after removal of the wash water, were Table II Semi-refined na htlienic Type of acidssci treated Same Same Home as indicatedabove Water wash None None Aggzetiiiii git-h Same. Clay used-amou. nt l7 Fl1ti-b1" 10%Filti'oP'- 107 Fi1 tro l" l07 Filtrol". Clay treating temperature 200 F 225 F 225 'F 225 1?. Duration of clay treating..; 2 min ,2 min 2 min 2 min. Color 0! filtrate 4% N. P. A--- 4% N. P. A..- 6% N. P. A--. 6% N. P. A.

blown bright with natural gas, at a temperature of about 180 F. They were transparent when viewed through the neck of a four oimce oil ,sample bottle, whereasthe untreated acids were black and had no such transparency.

The naphthenic acids which had been purified as indicated above were then mixed at room temperaturewith approximately 10% by weight of Filtrol. Individual samples of the mixture were slowly heated up to a temperature of approximately 212 F. to cause a dehydration of the adsorbent in such a manner that no undue mixture of naphthenic acid and clay was allowed to remain at this temperature for approximately two minutes. The acids were then removed from the adsorbent materials by passing the mixture through a suitable filtering device. This filtrationwas carried out at substantially the same elevated temperature which prevailed during the clay treatment which greatly facilitated the rate of filtration.

The finished product has a permanent color of from 4% to N. P. A. and was of a bland to sweet odor as may be seen from the following table:

In case an extremely light colored product such as one having a color of between 2 and 3 N. P. A. is desired, the treatment with the adsorbent material, or with an adsorbent material which has been activated by means of sulphuric acid, phosphoric acid or the like, or by means of an acid salt as indicated above, may be repeated. Thus, a product having a color of 3 N. P. A. was obtained by treating naphthenlc acids which had been purified as indicated above and which had a color of 4% N. P. A. with 10% of Filtrol which had been activated by means of 0.33% of 60% sulphuric acid, at a temperature of 325 A small amount of water (10% .by

volume of the naphthenic acids) was added to means of concentrated aqueous solution of ferric chloride or zinc chloride in amounts substan-, tially the same as used in the case of the incrganic acids described above, or by passing dry Table I hydrogen chloride or other hydrogen halides into emifined Semi-refined Semi-refined I stock treated i i 8 31 acid acid Volume of acid treat 5vo1.% o! 80% i5 vol.% oi 80% 5 vol.% of 80% 5 vol.% oi.80%

. H 04. H1304. H Adsorbent Filtrol Filtrol "Filtrol" Fi ltroL' Temperature 0! "Filtrol trea 75 F 225' F 250 F 300 F. Duration of FiltroP treat- 2 min... min 2 mm 2 Color of stock.-. Black Blariq. P A Color of finished product... 8131 2 1 im- 4% I the naphthenic acids containing the carbonaceous materials, or by treating the impure naphthenic acids with concentrated aqueous solutions of hydrogen halides. The function of any of the above reagents is to coagulate the carbonaceous 0 materials to particles large enough'to settle under the influence of gravity. I have discovered that naphthenic acidswhich have been freed from carbonaceous material by means of any of the above mentioned reagents are readily amenable to treatment with an adsorbent material in the manner described above. While the process of deodorization and decolorization has been particularly described in connection with phenol-free or semi-refined" naphthenic acids, it may equally well be applied to naphthenic acids which have not been subjected to a process for theremoval of phenolic materials such as that previously described. However, such products do not possess as desirable a color and odor ,as the naphthenic acids which had been freed from phenolic material. The term blowing bright referred to earlier in this specification, relates to the treatment of and the like, for removing traces of water which remain in the naphthenic acids or other liquid hydrocarbon after a treatment thereof with wat'er or aqueous solutions.

The term Filtrol signifies an acid treated clay'or fullers earth. The product commercially marketed under that name consists of fullers earth which has been activated by means .,of

dilute sulphuric acid.

The term N. P. A. color used in this specifl cation relates to a color grade of a liquid ob tained by means of the Union petroleum colorimeter adapted as a standard of the National Petroleum Association in 1915. Adetailed description of the apparatus, method of test and significance of scalereadings may be found in David T. Day's Handbook of Petroleum Ind., 1922, vol. 1; page 665. For example N. P. A. 0.5-1 indicates a. light, almost water-white color, wherein N. P. A. 3 indicates a yellow to straw color and N. P. A. '7

. to 8 indicates a product of a dark reddish to- The process herein set forth is applicable-to all varieties of naphthenic acids, It may be equally well applied to naphthenic acids derived from a light petroleum fraction such as kerosene as to acids derived from the higher boiling fractions such as gasoil or lubricating oil.

The examples set forth herein are merely illustrative of the generic invention and many variations thereof will be obvious to those smlled inthe art. 7 I claim:

1. A process for deodorizing and decolorizing crude naphthenic acids substantially free from carbonaceous materials which comprises treating said acids with an adsorbent material.

2. A process for deodorizing and decolorizing crude naphthenic acids substantially free from carbonaceous materials which comprises admixing said acids with anjadsorbent material, heating the mixture of naphthenic acids and adsorb= ent material we temperature in excess of normal room temperature and separating the spent adsorbent material from the naphthenic acids.

3. A process for deodorizing and decolorizing crude naphthenic acids which comprises contacting' said. acids with a reagent adapted to remove vii-carbonaceous materials admixed with the said -naphthenic acids and contacting the so treated naphthenic acids with an adsorbent material.

' 4. A process for deodorizing and decolorizing crude naphthenic acids which comprises removing carbonaceous materials admixed with the said naphthenic acids and subsequently treating the said naphthenic acids with an adsorbent material at temperatures in excess of normal room temperature.

5. A processfor deodorizing and decolorizing 'crude naphthenic acids which comprises contacting said acids with an oxygen-containing inorganic acid capable of removing carbonaceous materials admixed with the said naphthenic acids and contacting the so treated naphthenic acids with an adsorbent material at temperatures sub stantiall'y in excess of normal room temperature.

6. A process for deodorizing .and decolorizing crude-naphthenic acids which comprises contacting said acids with sulphuric acid having a concentration between approximately 50 and 83% to remove carbonaceous materials admixed with the said naphthenic acids, and contacting the so treated naphthenic acids with an adsorbent material at temperatures substantially in excess of normal room temperature.

7. A process for deodorizing and decolorizing crude naphthenic acids which comprises contacting said acids with sulphuric acid to remove carbonaceous materials admixed withthe said naphthenic acids. and contacting the so treated naphthenic acids with an adsorbent material at temperatures substantially in excess of normal room temperature.

8. A process for deodorizing and decolorizing crude naphthenic acids which comprises contacting said acids with sulphuric acid having-a concentration between approximately 83% H2504 and about 15% dissolved $03, in the presence of a light hydrocarbon to obtain a naphthenic acid "phase comprising naphthenic acids dissolved in' said light hydrocarbon and a phase comprising acid sludge and carbonaceous materials originally admixed with the said naphthenic acids, separating the two phases and contacting the naphthenic acid phase with an adsorbent material at temperatures in excess of normal room temperature.

I 9. A process for deodorizing and decolorizing crude naphthenic acids which comprises contacting said acids "with sulphuric acid having a concentration of approximately in the presence 'of a light hydrocarbon to obtain a naphthenic acid phase comprising naphthenic acids dissolved in said light hydrocarbon and a phase comprising acid sludge and carbonaceous materials originally admixed with the said naphthenic acids,

separating the two phases and contacting the naphthenic acid phase with an adsorbent material at temperatures in excess of normal room temperature.

10. A process for deodoriz'ing and decolorizing crude naphthenic acids which. comprises removing carbonaceous materials admixed with the said naphthenic acids and subsequently treating said naphthenic acids with an adsorbent material at temperatures which are below the boiling point of the said naphthenic acids.

. 11. A process for decdorizing and decolorizing' 12. A process for deodorizing and decolorizing crude naphthenic acids which comprises removing carbonaceous materials admixed with the said naphthenic acids and subsequently treating said naphthenic acids with an adsorbent material in the presence of an inorganic substance capable of liberating hydrogen ions, at temperatures substantially inexcess 'of normal room temperature.

13. A process for deodorizing and decolorizing crude naphthenic acids which comprises removing carbonaceous materials admixed with the said naphthenic acids and subsequently treating said naphthenic acids with an adsorbent material in the presence of an inorganic acid sulfate capable of liberating hydrogen ions at temperatures substantially in excess of normal room temperature.

14. A process according to claim 6 in which the adsorbent used in .iullers earth which has been activated with sulphuric acid.

15. A process for deodorizing and decolorizing crude naphthenic acids which comprises contacting said acids with sulphuric acid, removing sludge and carbonaceous materials which have been agglomerated due to the action-of the sulphuric acid without removing the residual sulphuric acid remaining admixed with the naphthenic acids, contacting the naphthenic acids at elevated temperatures with an adsorbent material in the presence of said residual sulphuric acid and separating the spent adsorbent material from the naphthenic acids.

16. A process according to claim 15 comprising the additional step of incorporating a small amount of water into the mixture of naphthenic acids, residual sulphuric acid and adsorbent material for the purpose of realizing a more efflcient activation of the adsorbent material by the residual sulphuric acid.

17. A process for deodorizing and decolorizing crude naphthenic acids which comprises contacting said acids with sulphuric acid having a concentration between approximately 50 and 83% to remove carbonaceous materials admixed with the said naphthenic acids, removing acid sludge together with the carbonaceous materials from the naphthenic acids, water washing the naphthenic acids to remove residual sulphuric acid, blowing the naphthenic acids with an inert gas to remove the remaining traces of water and contacting the so treated naphthenic acids with an adsorbent material at temperatures substan tially in excess of normal room temperature.

18. A. process according to claim 17 in which the adsorbent used has been activated with an inorganic acid.

19. A process for deodorizing and decolorizing crude naphthenic acids which comprises contacting said acids with sulphuric acid having a con centration between approximately 50 and 83% at 'a temperature substantially in excess of normal room temperature, removing carbonaceous materials and acid sludge from the naphthenic acids and contacting the so treated naphthenic acids with an adsorbent material at temperatures substantially in excessof normal room temperature.

20. A process for deodorizin'g and decolorizing crude naphthenic acids which comprises contacting said acids with sulphuric acid having a concentration between approximately 83% H280; and about 15% dissolved S03, at a temperature substantially in excess of normal room temperature, removing carbonaceous materials and acid sludge from the naphthenic acids and contacting the so treated naphthenic acids with an adsorbent material at temperatures substantially in excess of normal room temperature.

21. A process for deodorizing and decolorizing crude naphthenic acids which comprises contacting said acids in the presence of a light hydrocarbon with a reagent adapted to remove carbonaceous materials admixed with the said naphthenic acids, separating a naphthenic acid phase less than approximately 83% H2804 to the mixture of naphthenic acids and sulfuric acid to obtain a naphthenic acid phase and a phase comprising acid sludge and carbonaceous materials, separating said phases and treating the naphthenic acid phase with an adsorbent material at temperatures in .excess of normal room temperature.

FREDERICK J. EWING.

. CERTIFICATE OF CORRECTION. I f 7 zte nt No. 2,035,742, March 31, 1936.

FREDERICK J-. EKWING. y

It is hereby certified that error appears in the printed specification'of he above numbered patent requiring correction as follows: Page 4, 'Table I, n next to last column thereof, last line, for "N. read N. P". 'A.

; p 'irst column, line 20, claim 14, for "in" read is; and that the said Letters 'atent should be read with these corrections therein that the same may con-1 orm to the record of the case in the Patent Office.

Signed and sealed this 2nd day of February, A; D. 1937.

Leslie Frazer :eal) Acting Commissioner of Patents. 

